1. Field of the Invention
This specification relates to an electric motor and an electric vehicle having the same, and particularly, to an electric motor capable of reducing material costs and improving an output.
2. Background of the Invention
Recently, demands or uses of electric vehicles or hybrid vehicles (hereinafter, referred to as ‘electric vehicle’), which use an electric motor as a power source or auxiliary power source, are increasing due to environmental pollution caused by exhaust gases from vehicles or automobiles, fossil fuel depletion and the like.
The electric motor may include a casing, a stator disposed within the casing, and a rotor disposed to be rotatable with respect to the stator.
The stator may generate heat due to copper loss (wire loss) and/or core loss during operation.
The rotor may use permanent magnets for enhancing power density.
Here, the electric motor used in the electric vehicle should provide high power density, and accordingly, be required to have a relatively high cooling performance.
The related art electric motor for the electric vehicle generates high heat during running. Accordingly, upon using the permanent magnets, the permanent magnets should exhibit less change in magnetic properties even at high temperature.
However, a permanent magnet, which exhibits such less change in the magnetic property even at the high temperature, is relatively expensive, which causes an increase in a material (permanent magnet) cost.
Furthermore, the related art electric motor for the electric vehicle is configured such that a cooling unit for cooling the electric motor cools the casing as well, which causes limitation on lowering temperature of the stator, which actually generates heat. Accordingly, there may be a limit to enhancing the output of the electric motor.